Various recording apparatus are used to form images on recording media. For example, computer-to-plate systems (also known as CTP systems) are used to form images on printing plates. A plurality of imaged printing plates is subsequently provided to a printing press where images from the printing plate are transferred to paper or other suitable surfaces. It is important that the plurality of images be accurately aligned with respect to one another to ensure an accurate registration among the images. It is important that each image be geometrically correct and free from distortion to ensure desired quality characteristics of the finished printed article. Geometric characteristics of an image can involve, but are not limited to: a desired size of an image portion or a desired alignment of one image portion with another image portion.
The geometric accuracy of the images formed on a recording media is dependant on numerous factors. For example, images can be formed on a recording media by mounting the media on a support and directing imaging beams towards the media to form the images thereupon. Images can be formed by scanning the recording media with the imaging beams during a plurality of scans. The positioning accuracy of the imaging beams with respect to the recording media impacts the geometric correctness of the formed images. Deviations in required positioning of the imaging beams during each scan can lead to imaging errors.
In order to reduce imaging errors, recording systems are typically calibrated. Calibration images are typically formed on recording media and are analyzed to determine deviations. Deviations associated with a desired geometric characteristic of a calibration image are typically corrected by performing various adjustments in the recording systems. The adjustments can be electronic or mechanical in nature. Analysis of the calibration images is typically performed on specialized and dedicated equipment that can include various image capture sensors. For example CCD sensors can be used to capture various images of the calibration images and a controller can be used to analyze the captured images and determine calibration information therefrom.
Specialized and dedicated calibration systems are costly and require regular calibration themselves to insure their integrity. Such systems are typically employed at the factory where the recording systems are manufactured. Use of factory based calibration systems complicate the calibration of a recording system in the field. For instance, test images would need to be made in the field and then shipped to another site for analysis. This increases the time required for calibration and increases the chances for imaging errors to occur. Therefore, there is a need for effective and practical methods and systems that permit the calibration of a recording apparatus to correct geometric distortions of images formed on a recording media by the recording apparatus.